Preparation of protein concentrates by centrifuging a wheat flour slurry in the presence of corn oil and soybean protein or lecithin



United States Patent Oflice US. Cl. 260112 2 Claims ABSTRACT OF THEDISCLOSURE Protein concentrates are prepared from wheat flour by thefollowing technique: The flour is slurried with water and an ediblegluten-modifying agent such as mixtures of soybean protein and corn oil,and lecithin and corn Oil. The slurry is then centrifuged, yielding asupernatant liquid which contains essentially all the proteins of theflour. This liquid may be dried and used as a protein supplement inbread and other foods.

This is a division of my copending application Ser. No. 789,556, filledDec. 20, 1968, now US. Pat. 3,501,- 451, which in turn is a division ofSer. No. 556,823, filed June 8, 1966, now Pat. No. 3,463,770.

A non-exclusive, irrevocable, royalty-free license in the inventionherein described, throughout the world for all purposes of the UnitedStates Government, with the power to grant sublicenses for suchpurposes, is hereby granted to the Government of the United States ofAmerica.

This invention relates to and has among its objects the provision ofnovel processes for preparing protein concentrates from wheat flour.Further objects of the invention will be evident from the followingdescription wherein parts and percentages are by weight unless otherwisespecified.

It is well known that wheat flour contains valuable proteins plusvarious other components, primarily starch. For certain purposes it isdesirable to treatthe flour to obtain compositions which contain anincreased proportion of protein. Such procedures are generallycumbersome because of the tendency of the flour to form sticky masses ordoughs when incorporated with water and subjected to such manipulationsas centrifugation.

By application of the process of the invention this stickiness problemis obviated with the result that the protein and starch components canbe efiectively separated.

In a practice of the invention the following procedureis employed:

A slurry of wheat flour, water, and an edible glutenmodifying agent isprepared. In preparing this slurry, one generally uses about 1 to 3parts of water per part of flour. A preferred proportion which providesa slurry thin enough for easy handling, yet employs a minimum of water(to reduce the expense of drying the protein concentrate eventuallyobtained), is 1.5 parts of water per part of flour. The criticalcomponent in the slurry is the gluten-modifying agent. This substanceexerts the important effect of modifying the wheat protein (gluten) sothat its tendency to form a dough or other sticky material is markedlydecreased.

In preparing the slurry, the three components-flour, water, andgluten-modifying agent-may be combined all at once. Alternatively, theother components may be added sequentially to the water. Preferably,where the Patented Nov. 24, 1970 gluten-modifying agent is awater-soluble material, the following technique is used: Thegluten-modifying agent is dissolved in the water. Then, the flour isincorporated in the resulting solution to form the slurry. Where thegluten-modifying agent is a water-insoluble material-for example, anedible oil-the following technique is preferred: A part of the flour(for example, one-fourth of the total amount) is incorporated with thewater, the oil is then stirred in, and finally the remainder of theflour is incorporated into the system.

Having prepared the slurry of water, flour, and glutenmodifying agent,this slurry is then subjected to centrifugation. This causes formationof a system containing plural phases: A dense bottom phase; asupernatant liquid phase; and, in some cases, a sludge phase between thebottom phase and the supernatant liquid phase. The bottom phase containsessentially all the prime starch from the flour in almost a pure state.This prime starch phase being in a granular condition, completely freefrom stickiness, can be readily separated from the remainder of thesystem, and can be readily processed as by washing with water and dryingto prepare a high grade starch for any desired use. Essentially all theprotein from the flour is contained in the supernatant liquid, ordivided between the supernatant and sludge phase where both are present.Both the supernatant and sludge phases are free from stickiness andgumminess so that they can be readily handled, removed from the starchphase, etc. The supernatant liquid and the combined supernatant andsludge phases where both are present constitute valuable proteinconcentrates useful for many purposes. Typically, the proteinconcentrates may be dried and used as a protein supplement in bread andother foods, in mixed animal feeds, etc. Also, the pro tein concentratescan be used as a base for preparing milklike beverages.

In accordance with the invention various substances may be employed asthe gluten-modifying agent, for example: Water-soluble proteins such assoybean protein, gelatin, sodium caseinate, and substances containingcasein, e.g., dried milk; edible (glyceride) oils, such as soybean oil,peanut oil, corn oil, cottonseed oil, safliower oil, olive oil, and thelike; water-soluble cellulosic gums such as methyl cellulose andcarboxymethyl cellulose; phospholipids such as lecithin and cephalin.These sub stances may be used individually or as admixtures of two ormore. The gluten-modifying agent is operative over a wide range ofproportions. Usually, it is preferred to use the minimum effectiveamount of the agent and generally this will be in the range from about/2 to about 5 parts thereof per parts of flour. Larger proportions maybe usedfor example, up to 30 parts per 100 parts of flourbut they exertlittle, if any, extra benefit.

In the process of the invention, essentially all of the addedgluten-modifying agent appears in the protein concentrate; that is, itis in the supernatant liquid or divided between the supernatant andsludge layers where both of these phases are present. The occurrence ofthe additive in the final product is not a detriment because it is anedible material and may even add to the nutritive value of the proteinconcentrate. This is the case, for example, 'where the additive is aprotein or edible oil. The presence of the edible oil in the proteinconcentrate is especially desirable where the latter is to be convertedinto a milklike beverage of full-fat character in that no extra fat needbe added to achieve this end.

Ordinarily, for convenience, the slurry of flour, water, andgluten-modifying agent is prepared at room temperature. However, it hasbeen observed that special benefits are attained at lower temperatures,i.e., the intermediate sludge layer has a more liquid character and iseasier to remove from the centrifuge. Accordingly, in a preferredmodification of the invention, the slurry is prepared in the cold, thatis, at a temperature below room temperature but not so low as to causethe slurry to become frozen. For best results, the temperature islowered to a point just above freezing, for example, about a degreeabove 32 F. so that the slurry remains a liquid. The benefit of thelowered temperature is primarily achieved when the slurry is prepared inthe cold. However, it is also beneficial to maintain the low temperaturewhen the slurry is centrifuged.

The invention is further demonstrated by the following illustrativeexamples.

'EXAMPLE 1 Corn oil Starch Increase in added, moved, perconcentrationpercent cent (dry of protein,

(on wt basis, on wt. percent of flour) of flour) (dry basis) EXAMPLE 2The procedure of Example 1 was repeated substituting various otheragents for the corn oil. In all cases it was observed that the slurry oncentrifugation separated properly into the supernatant liquid and primestarch phases.

and starch layers could be separated easil and completely.

A particularly important advantage of the invention is that it yieldsprotein concentrates which contain valuable components which arenormally lost in conventional procedures for separating the starch andprotein components of wheat flour. This feature of the invention will beevident from the following explanation:

'In conventional methods, a dough of flour and water is formed and thensubjected to kneading while exposed to sprays of water. In thisoperation the starch and watersoluble components are washed away,leaving a mass of gluten. Starch is readily recovered from the washwater because it is suspended (not dissolved) therein. Thus, it caneasily be segregated by flowing the water over rifiies or the like.However, the substances that are actually dissolved cannot beeffectively recovered because of their soluble character and the largevolume of wash water in which they exist. These soluble componentsinclude watersoluble proteins, vitamins of the B group, minerals, andsugars. It may be noted that the water-soluble proteins are mostlyalbumins which are particularly desired from a nutritive standpoint inthat they contain a balanced proportion of amino acids, Gluten, incontrast, is deficient in the essential amino acid lysine. It is evidentfrom the above explanation that the conventional procedure yields aprotein concentrate, i.e., gluten, which is lacking in the valuablewater-soluble components of the flour. In contrast, however, theinvention surmounts this deficiency in that the protein concentratescontain all the desired components of the flour, including those of awater-soluble nature, e. g., water-soluble proteins, vitamins, mineralsand sugars. Thus in the process of the invention, the centrifugationcauses a segregation only of the prime starch; the desiredcomponents-including the gluten and the water-soluble proteins,vitamins, minerals, and sugars-are concentrated in the supernatantliquid phase (or in the supernatant and sludge phases, where both arepresent).

Starch Increase in removed, concentration percent (dry of wheat pro-Addltive and proportion thereof, pcrbasis on wt. tein, percent cent(based on wt. of flour) of flour) (dry basis) Run:

4 Soybean protein, 5 55.0 200 5." Soybean protein, 15 52 159 6... 46 1807 44 167 Soybean protein, 5; c n 0 60 201 atin, 15 58 140 Lecithin, 5;corn oil, 4.5. 48 163 EXAMPLE 3 50 Accordingly, the concentratesproduced in accordance A Series of runs were made usmg the followmg techwith the invention constitute compositlons of matter not nrque:

Wheat flour (1 part) was slurried with water (1.5 parts). To differentlots of the slurry was added, with stirring, non-fat dry milk solids invarious proportions (given below). In one of the runs, nothing was addedto provide comparative data. The slurries were then centrifuged for 5minutes at 1500 rpm. The results are tabulated below:

Amount of Increase in non-fat dry Starch concentration milk solidsremoved, of wheat added, perpercent protein, cent (based on (dry basison percent wt. of flour) wt. of flour) (dry basis) 1 None added.

It was further observed that in Run 11, the centrifuged material wassticky and gummy so that it was diflicult to separate the starch fromthe supernatant. In Runs 12 and 13 the centrifuged material was in twophases: Prime starch and supernatant liquid. Moreover, in these runsthere was no stickiness or gumminess and the supernatant hitherto knownand which posses significant advantages over the known concentrates.

Having thus described the invention, what is claimed is: 1. A method forpreparing a protein concentrate from wheat flour which comprises (a)preparing a slurry of wheat flour, water, and an edible gluten-modifyingagent to decrease the tendency of the flour to form a dough, theproportion of water being 1 to 3 parts thereof per part of flour, theproportion of gluten-modifying agent being 0.5 to 30 parts thereof perparts of flour, (b) centrifuging the slurry to segregate the starch fromthe proteinous components of the flour, and (c) removing the segregatedstarch to obtain a proteinous composition of increased proteinconcentration, (d) the said gluten-modifying agent being an admixture ofsoybean protein and corn oil. 2. A method for preparing a proteinconcentrate from wheat fiour which comprises (a) preparing a slurry ofwheat flour, water, and an edible gluten-modifying agent to decrease thetendency of the flour to form a dought, the proportion of water being 1to 3 parts thereof per part of flour,

the proportion of gluten-modifying agent being 0.5 to 30 parts thereofper 100 parts of flour,

(b) centrifuging the slurry to segregate the starch from the proteinouscomponents of the flour, and

(c) removing the segregated starch to obtain a proteinous composition ofincreased protein concentration,

(d) the said gluten-modifying agent being an admixture of lecithin andcorn oil.

References Cited UNITED STATES PATENTS 1/1912 Klopfer 1954 6/ 1948 Walshet a1. 19511 12/1948 Dimlcr 12767 2/1949 Lowcn 106136 7/ 1950 Harrel cta1. 12767 6/ 1951 Kilander 99-50 Chem.

OTHER REFERENCES Chem. Abstracts, vol. 2, 1908 (187, 590), Klopfer, 919.Chem. Abstracts, vol. 3, 1909 (929, 861), Klopfer,

Howard et a1.

Chem. Abstracts, vol. 53, 1959, 22561i, 22562a, Kisaki.

Chem. Abstracts, vol. 27, 1933, 4315(1), Fisher et a1. Abstracts, vol.52, 1958, 17429i-17430a-b,

Chem. Abstracts, v01. 60, 1964, 2252a-h, Katsuya et a1.

WILLIAM SHORT, Primaly Examiner H. SCHAIN, Assistant Examiner

